Stream of mist between objects?
Make a smoke sim. Model flowing branches, set as smoke flow. Set Density to desired opacity. Set temp diff to 0. run sim. add balls at smoke termination points. 

If you want it in motion, give balls a negative (-500) force field, raise temp diff slightly to .05, set dissolve time to 1 in domain, lower temp diff and vorticity in domain to taste. 

In all cases you'll want to hide the original smoke model.